(1) Field of the Invention
This invention relates to a rear view mirror for a motor vehicle, which is movable automatically between a normal viewing position and an anti-glare position in which glare from light reflected from the mirror is reduced.
(2) Description of the Prior Art
Automatically adjusting rear view mirrors are known as shown by the following patents in which such mirrors have been proposed.
U.S. Pat. No. 3,152,216 to M. L. Woodward
W. German Offenlegungsschrift No. 2 133 182 to G. Paul
British Pat. No. 1 346 483 to K. A. Grell
French Pat. No. 1 463 007 to Chipoff et Perrier U.S. Pat. No. 3,152,216 discloses an automobile rear view mirror comprising a housing that receives a mirror glass and an arrangement which automatically pivots the mirror from its normal viewing position to an anti-glare position in response to headlights of a following car shining into the mirror. The mirror glass has an unsilvered portion to which is attached a photodetector for detecting light incident on the mirror. The assembly of the photodetector and the mirror glass is mounted on a metal plate which is pivotally mounted on a bracket centrally of the mirror glass, the bracket being mounted in the housing. The bracket also carries an electrical circuit including a thermionic valve responsive to the photodetector and which drives a relay to operate in response to a predetermined light level incident on the photodetector. The relay is arranged to switch electric current to a solenoid coil in such a manner that the coil attracts the metal plate and thereby pivots the mirror to its anti-glare position.
A disadvantage of this prior art mirror is that it is relatively complex and expensive to produce particularly because the photodetector has to be mounted separately from the rest of the circuitry on a separate bracket on the mirror, and also because metal pivot joints and a metal bracket are required to pivotally mount the mirror in the housing. Also, the valve driven circuitry is relatively bulky and is relatively insensitive to incident light due to the fact that it requires a relay to switch current to the solenoid coil.